objects get sliced with no bottom or top layers

[mopswachtel]

when my objects get sliced wothout top and bottom layers although I set up 2 top an bottom shells in the print settings.
When it comes to printing, objects get printed without bottom an top layers according to the preview model.

I can't figure out what is causing this Problem. I occurs with every sourcefile I tested.

[BaudR8]

I've found this is almost always an issue with the model not being 100% correct. If you post up the model we can take a look at it to see what's going on. A factory file would be even better, which will save your model and process(es) for others to import.

try going to repair > identify non-manifold, if errors appear, it's most likely that that's causing it not to slice properly